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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 998 (Transfer Case - NVG 263-NP1) >> Diagnostic Information and Procedures >> DTC B2725: ATC Mode Switch Circuit Malfunction >> Test Description

Test Description

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The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step tests for proper operation of the transfer case mode select switch.
  2. 3:  This step tests the mode switch for proper resistance values in all mode switch states.
  3. 4:  This step tests the switch signal wire for a short to ground, short to voltage, or high resistance
DTC B2725

Step Action Values Yes No
Schematic Reference: Transfer Case Control Schematics 
Connector End View Reference: Transfer Case Control Connector End Views 
1 Did you perform the Diagnostic System Check - Transfer Case? - Go to Step 2  Go to Diagnostic System Check - Transfer Case 
2 
  1. Install a scan tool.
  2. Start the engine.
  3. Set the parking brake.
  4. Place the transmission into Neutral.
  5. With a scan tool, observe the mode switch selected in the tech 2 transfer case data list.
  6. Select each of the modes.
Does the scan tool indicate that the modes are in the correct state while pressing the mode buttons?		 - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3 
  1. With the switch disconnected, connect a DMM between the mode switch signal circuit and the 5 volt reference circuit at the switch.
  2. Measure the resistance through the mode switch while pressing and holding each of the mode buttons and comparing values.
Does the DMM indicate all resistance values within the specified ranges?		 Normal: 8,635-9,544 Ω
4 HI: 630-696 Ω
2 HI: 1,440-1,592 Ω
Neutral: 974-1,035 Ω
4 LO: 2,228-2,462 Ω		 Go to Step 4  Go to Step 5 
4  Test the switch signal and 5 volt reference circuits for a short to voltage, short to ground or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 7  Go to Step 6 
5 Replace the mode switch. Refer to Transfer Case Shift Control Switch Replacement .
Did you complete the repair?		 - Go to Step 7  -
6 Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement  and Transfer Case Control Module Reprogramming .
Did you complete the repair?		 - Go to Step 7  -
7
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC set?		 - Go to Step 2  System OK
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